In general, an LED is an element in which electrons and holes are combined in a P-N semiconductor junction structure by application of current thereby emitting certain light. The LED is typically formed to have a package structure, in which an LED chip is mounted, and is frequently referred to as an “LED package.” Such an LED package is generally mounted on a printed circuit board (PCB) and receives current applied from electrodes formed on the PCB to thereby emit light.
In an LED package, heat generated from an LED chip has a direct influence on the light emitting performance and life span of the LED package. The reason is that when heat generated from the LED chip remains for a long period of time, dislocation and mismatch occur in a crystal structure of the LED chip. Moreover, a high power LED package has been recently developed. Since the high power LED package is operated by high-voltage power and a large amount of heat is generated in an LED chip due to the high voltage, a separate device for effectively dissipating the generated heat is required.
Therefore, there has been developed a conventional LED package for enhancing heat dissipation performance using a metal printed circuit board (metal PCB) in which an insulating layer and a metal pattern layer are sequentially formed on an aluminum base. For example, such a conventional LED package is fabricated in such a manner that a hole cup is formed in the aluminum base so that a portion of the aluminum base is exposed upward by a groove machining process such as cutting, an LED chip adheres to the hole cup, and then the LED chip and the metal pattern layer are connected to each other through a conductive wire.
However, the conventional LED package is difficult to be fabricated into a compact structure due to a large thickness of the aluminum base, and does not have a lead structure for electrically connecting the LED chip to external electrodes. For this reason, it may be difficult to mount the conventional LED package on a typically used PCB. This means that the conventional LED package is less compatible with a conventional electronic device or is illumination device. Since current LED package manufacturers mostly have equipments suitable for fabricating LED packages with a lead structure, the conventional LED package limits the use of the existent equipments as described above. For this reason, the conventional LED package is also uneconomical.
Additionally, in the conventional LED package, since the hole cup is formed by a groove machining process such as a cutting process, the mounting surface of an LED chip is uneven due to the groove machining process, which causes a die attaching process of an LED chip to be difficult. In addition, the die-attached LED chip may be easily damaged due to thermal and mechanical impact.
An object of the present invention is to provide an LED package having a metal PCB, which has a superior heat dissipation property and a compact structure, does not largely restrict use of conventional equipments, and is compatible with an electronic device or illumination device currently used widely.
An LED package according to an aspect of the present invention comprises a metal printed circuit board (PCB) formed by laminating first and second sheet metal plates with an electric insulating layer interposed therebetween; and an LED chip mounted on the first sheet metal plate of the metal PCB, wherein the first sheet metal plate has electrode patterns and leads respectively extending from the electrode patterns.
At this time, each of the leads is preferably formed by bending a portion of the first sheet metal plate extending in an outer side direction from the metal PCB. More preferably, each of the leads has an enlarged contact area with an external electrode through two-step bending of the portion of the first sheet metal plate. Accordingly, each lead can have an enlarged contact area with an external electrode.
Alternatively, each of the leads may comprises a terminal pattern formed by patterning the second sheet metal plate in correspondence to the electrode pattern; and a via conductive portion passing through the metal PCB to connect the electrode pattern and the terminal pattern.
According to preferred embodiments of the present invention, the first and second sheet metal plates may be made of copper or copper alloy. The LED package may further comprise a molding member formed on the first sheet metal plate to cover the LED chip. The LED package may further comprise a hole cup formed around the LED chip to adjust a directional angle of light emitted from the LED chip. The hole cup may be formed of resin, metal, ceramic or a composite thereof. The hole cup may be made of an FR4 material. Further, the hole cup may include an insulating plate and a metal reflective plate, each of which has an opening, and which are sequentially formed on the first sheet metal plate. In addition, the metal reflective plate may be made of aluminum.